When a team is winning and looking good, everything a HC says sounds great. When a team is losing and looking like crap, everything a HC says sounds dumb. That's the game.
Diaz's team has looked unprepared and played below expectations for two straight weeks (and really, four straight weeks if we're going back to 2020). No matter what he says, nobody is going to be happy. There is literally nothing (other than "I resign") that Diaz could say on the radio or following practice that would change anybody's mind about the state of the program. Notwithstanding all of that, as HC Diaz remains obligated to attend his radio spots, post-game press conferences, and post-practice press conferences.
I am not sure what people expect the man to say or why anyone cares at this point. If you think Diaz should go, nothing he says will change that. If you still believe in Diaz at this point, then nothing he says will change that either. Only the play on the field matters.